This program project includes three research components that are concerned with testing alternative hypotheses about the most scientifically reasonable and efficient methods for ameliorating the deficits of mentally retarded children in learning, retention, and a variety of cognitive processes. Two of the projects operate from the premise that mentally retarded children manifest a retrieval deficit because of an irreversibly chaotic input system. One of these projects has a series of laboratory studies, completed and under way, that are investigating the effects on the storage and retrieval behavior of retarded children of a variety of techniques for increasing the saliency of redundancy and other organizational cues in stimulus materials. The second of these projects is evaluating the effectiveness of input structure in a classroom setting. Specifically, it is investigating the effects of defined forms (commonality, progression, theme activity, etc.) of curriculum organization on the learning of academic content by mentally retarded children. The third project suggests that the input structure deficiency of the mentally retarded may be remediable. The studies in progress are attempting to develop stable predispositions in the mentally retarded to structure and organize stimulus inputs over a wide range of content.